Modification of Visual Approach Slope Indicator Baffles at Pearson Field Airpark, Vancouver, WA
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a Modification of Visual Approach Slope Indicator Baffles at Pearson Field Airpark, Vancouver, WA James W. Patterson, Jr. June 2007 DOT/FAA/AR-TN07/12 This document is available to the public through the National Technical Information Service (NTIS), Springfield Virginia 22161 U.S. Department of Transportation Federal Aviation Administration te technical note technic o NOTICE This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein solely because they are considered essential to the objective of this report. This document does not constitute FAA certification policy. Consult your local airports office as to its use. This report is available at the Federal Aviation Administration William J. Hughes Technical Center's Full-Text Technical Reports page: actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF). Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. DOT/FAA/AR-TN07/12 4. Title and Subtitle 5. Report Date MODIFICATION OF VISUAL APPROACH SLOPE INDICATOR June 2007 BAFFLES AT PEARSON FIELD AIRPARK, VANCOUVER, WA 6. Performing Organization Code AJP-6311 7. Author(s) 8. Performing Organization Report No. James W. Patterson, Jr. 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Federal Aviation Administration William J. Hughes Technical Center Airport and Aircraft Safety Research and Development Division Airport Technology Research and Development Branch Atlantic City International Airport, NJ 08405 11. Contract or Grant No. 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered U.S. Department of Transportation Technical Note Federal Aviation Administration Operations Engineering Group, Infrastructure Support Center-Seattle FAA Northwest Mountain Regional Office 1601 Lind Ave, SW Renton, WA 98057 14. Sponsoring Agency Code AJW-W23 15. Supplementary Notes Paul Jones of AJP-6311, Jim Newman and Nelson Brown of Hi-Tec Systems, Stacey Campbell of the FAA Portland Terminal System Support Center, and lead civil engineer Thinh Vu of the FAA Northwest-Mountain Region provided support throughout the course of the evaluation. 16. Abstract This technical note describes a research effort that was accomplished to correct a safety deficiency with a Visual Approach Slope Indicator (VASI) system at the Pearson Field Airpark in Vancouver, Washington. During a recent inspection flight, the VASI system was found to be emitting signals that could potentially draw an approaching aircraft dangerously close to an obstruction near the final approach path. As a result, the system was shutdown. The VASI system had baffles previously installed on the inside and on the front opening of the unit that were intended to limit the emission of light in the direction of the obstruction. The baffles were found to have very comparable opening widths in all units of the system, which allowed the signal from some units to be visible within a very close proximity to an obstruction. Typically, each opening requires a different width to provide proper signal blocking at the specific location of the obstruction. The Federal Aviation Administration Northwest-Mountain Region, Navigational Surveillance Weather Systems Team requested the Airport Technology Research and Development Branch’s assistance in correcting the misaligned baffles so that the VASI system could be restored to operation. Engineers from the Airport Technology Research and Development Branch visited the site to analyze the problem; collect data on the geometry of the obstruction, the baffles, and the general layout of the airport; and install and test the new baffles to make sure they operate properly. Engineers designed, constructed, and installed aluminum baffles that blocked the signal from the obstruction area, and provided a 2 degree margin of safety between the obstruction and the visible signal of the VASI. Ground and flight evaluations conducted by the Airport Technology Research and Development Branch verified that the installed baffles had eliminated the hazard by preventing a usable VASI signal from being seen near the obstruction. 17. Key Words 18. Distribution Statement Visual Approach Slope Indicator, Baffles, Baffling, Visual This document is available to the public through the National Aid, Pearson Field Airpark, Vancouver, Portland Technical Information Service (NTIS), Springfield, Virginia 22161. 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 24 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized TABLE OF CONTENTS Page EXECUTIVE SUMMARY vii INTRODUCTION 1 Purpose 1 Background 1 Scope 2 Objectives 2 Related Documents 3 DISCUSSION 3 EVALUATION APPROACH 6 Required Equipment 6 Method 6 Evaluation Process 8 RESULTS 8 CONCLUSIONS 9 APPENDICES A—Figures Indicating VASI Unit Measurements B—Photographs of the Site and Final Modification iii LIST OF FIGURES Figure Page 1 Diagram of VASI Unit Closer to Runway 8 Threshold 5 2 Diagram of VASI Unit Further From Runway 8 Threshold 5 iv LIST OF TABLES Table Page 1 Angles Measured From VASI Centerline to Indicated Line 6 v LIST OF ACRONYMS FAA Federal Aviation Administration mi Mile OR Oregon SCC System support center VASI Visual approach slope indicator VUO Pearson Field Airpark WA Washington vi EXECUTIVE SUMMARY This technical note describes a research effort that was accomplished to correct a safety deficiency with a Visual Approach Slope Indicator (VASI) system at the Pearson Field Airpark in Vancouver, Washington. During a recent inspection flight, the VASI units were found to be emitting a usable signal that could potentially draw an approaching aircraft dangerously close to an obstruction near the final approach path. As a result, the VASI system was shutdown. The VASI system had baffles previously installed on the inside and on the front opening of the unit that were intended to limit the emission of light in the direction of the obstruction. The baffles but were found to have very comparable opening widths in all units of the system, which allowed the signal from some units to be visible within a very close proximity to an obstruction. Typically, each opening requires a different width to provide proper signal blocking at the specific location of the obstruction. The Northwest-Mountain Region, Navigational Surveillance Weather Systems Team, AJW-W23, requested the Airport Technology Research and Development Branch’s assistance in correcting the misaligned baffles so that the VASI system could be restored to operation. Engineers from the Airport Technology Research and Development Branch visited the site to analyze the problem; collect data on the geometry of the obstruction, the baffles, and the general layout of the airport; and finally install and test the new baffles to make sure they operate properly. Engineers designed, constructed, and installed aluminum baffles that blocked the signal from the obstruction area, and provided a 2 degree margin of safety between the obstruction and the visible signal of the VASI. Ground and flight evaluations conducted by the Airport Technology Research and Development Branch verified that the installed baffles had eliminated the hazard by preventing usable VASI signals from being visible near the obstruction. vii/viii INTRODUCTION PURPOSE. The effort described in this technical note was accomplished in response to a request for assistance received from the Federal Aviation Administration (FAA) Northwest Mountain Region Navigational Surveillance Weather Systems Team, AJW-W23, to assist the Portland, Oregon (OR) FAA System Support Center (SSC). The request specifically involved modifying the Visual Approach Slope Indicator (VASI) system located at Pearson Field Airpark (VUO) in Vancouver, Washington (WA), herein referred to as Pearson. BACKGROUND. The VASI is a visual guidance device that is installed at an airport to provide vertical visual approach slope guidance to aircraft during approach and landing on a runway. A VASI system consists of light units that are specifically aimed at precise angles to produce a desired signal for the approaching pilot. The device radiates a directional pattern of high-intensity red and white focused light beams along the final approach path to the runway that the pilots use to determine their vertical position in relation to the desired glide slope. If the pilot sees red and white, he is “on glide path.” If the pilot sees white and white, he is “above glide path,” and if he sees red and red, he is “below glide path.” VASI units are constructed in metal box-like structures and have a bulkhead at the rear of the box that has three high-intensity lights mounted to it. Just in front of the lights, there are red filters positioned such that they cover one-half of the light’s surface. Depending on the height of the aircraft, the pilot will either see the red-filtered light or the white-unfiltered light through the narrow slot on the front of the VASI unit. These lights are typically visible from 3 to 5 miles (mi) during the day and up to 20 mi or more at night. The visual glide path of the VASI should provide safe obstruction clearance within plus or minus 10 degrees of the extended runway centerline. VASI installations may consist of a 2-, 4-, 6-, 12-, or 16-light unit arranged in bars, referred to as near, middle, and far bars. Most VASI installations consist of two bars, near and far, and may consist of a 2-, 4-, or 12-light unit. Some VASI systems consist of three bars, near, middle, and far, which provide an additional visual glide path to accommodate high-cockpit aircraft. This installation may consist of either a 6- or 16-light unit. VASI installations consisting of two-, four- or six-light units are usually located on just the left side of the runway.